<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>垂直框架</title>
</head>

<body>
    <frameset cols="25%,50%,25%">

        <frame src="./3.html">
            <frame src="./4.html">
                <frame src="./5.html">

    </frameset>


</body>

</html>